<template>
  <div class="create_canvas_style" @click="changeValidateCode">
    <canvas id="createIdentify" :width="contentWidth" :height="contentHeight"></canvas>
  </div>
</template>

<script>
    export default {
        name: "identify",
        props: {
          createCode: {
            type: String,
            default: '1234'
          },
          fontSizeMin: {
            type: Number,
            default: 16
          },
          fontSizeMax: {
            type: Number,
            default: 40
          },
          backgroundColorMin: {
            type: Number,
            default: 180
          },
          backgroundColorMax: {
            type: Number,
            default: 240
          },
          colorMin: {
            type: Number,
            default: 50
          },
          colorMax: {
            type: Number,
            default: 160
          },
          lineColorMin: {
            type: Number,
            default: 40
          },
          lineColorMax: {
            type: Number,
            default: 180
          },
          dotColorMin: {
            type: Number,
            default: 0
          },
          dotColorMax: {
            type: Number,
            default: 255
          },
          contentWidth: {
            type: Number,
            default: 115
          },
          contentHeight: {
            type: Number,
            default: 40
          }
        },
        methods: {
          changeValidateCode:function(){
              this.$emit("changeValidateCode",true);
          },
          // 生成一个随机数
          randomNum (min, max) {
            return Math.floor(Math.random() * (max - min) + min)
          },
          // 生成一个随机的颜色
          randomColor (min, max) {
            let r = this.randomNum(min, max)
            let g = this.randomNum(min, max)
            let b = this.randomNum(min, max)
            return 'rgb(' + r + ',' + g + ',' + b + ')'
          },
          drawPic () {
            let canvas = document.getElementById('createIdentify')
            let ctx = canvas.getContext('2d')
            ctx.textBaseline = 'bottom'
            // 绘制背景
            ctx.fillStyle = this.randomColor(this.backgroundColorMin, this.backgroundColorMax)
            ctx.fillRect(0, 0, this.contentWidth, this.contentHeight)
            // 绘制文字
            for (let i = 0; i < this.createCode.length; i++) {
              this.drawText(ctx, this.createCode[i], i)
            }
            // this.drawLine(ctx)  //绘制干扰线，增加难度
            this.drawDot(ctx)
          },
          drawText (ctx, txt, i) {
            ctx.fillStyle = this.randomColor(this.colorMin, this.colorMax)
            ctx.font = this.randomNum(this.fontSizeMin, this.fontSizeMax) + 'px SimHei'
            let x = (i + 1) * (this.contentWidth / (this.createCode.length + 1))
            let y = this.randomNum(this.fontSizeMax, this.contentHeight - 5)
            var deg = this.randomNum(-45, 45)
            // 修改坐标原点和旋转角度
            ctx.translate(x, y)
            ctx.rotate(deg * Math.PI / 180)
            ctx.fillText(txt, 0, 0)
            // 恢复坐标原点和旋转角度
            ctx.rotate(-deg * Math.PI / 180)
            ctx.translate(-x, -y)
          },
          drawLine (ctx) {
            // 绘制干扰线
            for (let i = 0; i < 8; i++) {
              ctx.strokeStyle = this.randomColor(this.lineColorMin, this.lineColorMax)
              ctx.beginPath()
              ctx.moveTo(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight))
              ctx.lineTo(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight))
              ctx.stroke()
            }
          },
          drawDot (ctx) {
            // 绘制干扰点
            for (let i = 0; i < 100; i++) {
              ctx.fillStyle = this.randomColor(0, 255)
              ctx.beginPath()
              ctx.arc(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight), 1, 0, 2 * Math.PI)
              ctx.fill()
            }
          }
        },
        watch: {
          createCode:function() {
            this.drawPic()
          }
        },
        mounted () {
          this.drawPic()
        }
    }
</script>

<style scoped>

</style>
